The density functional theory was employed to mimic the homogeneous hydro-dimerization of the Zeise-similar dichloro-bis(ethene)platinum(II), PtCl2(C2H4)(2). Three energy minima and four transition-states were involved in the reaction mechanism, which was even characterized by a catalytic cycle. The minima were fully optimized at B3LYP level whereas the transition-states were first individuated at the same level, by the synchronous transit-guided quasi-Newton method. then fully optimized. The mechanistic hypotheses on the PtCl2(C2H4)(2) dimerization implied the displacement of two ethene or two ethane molecules, respectively, occurring in absence or in presence of molecular hydrogen. In the second case, the dimer platinum product performed as a catalytic center. The study of the reaction paths as well as that of the structural and energetic transformations of the calculated species allowed us to deepen basis aspects of the title reaction. Whereas, a comparative analysis between some species involved in the same reaction and heterogeneous catalytic models, namely ethene on platinum-cluster models, fixed some analogies between the energetics involved in homogeneous and heterogeneous catalytic processes. (C) 2004 Elsevier B.V. All rights reserved.